1. Field of the Invention
The present invention relates to a method of manufacturing perovskite powder in the form of microparticles with excellent crystallinity and favorable dispersion properties, by the preparation of a high concentration and high purity metal oxide sol, as well as perovskite powder and a multilayer ceramic electronic component manufactured by the same.
2. Description of the Related Art
Perovskite powder is a ferroelectric ceramic material and broadly used as a raw material of electronic components such as a multilayer chip capacitor (MLCC), a ceramic filter, a piezoelectric device, a ferroelectric memory, a thermistor, a varistor, and the like.
Since electronic component manufacturers have recently tended to produce electronic components with decreased size and weight, increased capacity and improved reliability, ferroelectric particles are required to have a relatively small size, high dielectric constant and excellent reliability.
Conventional methods of manufacturing perovskite powder include a solid phase method and a wet process, and such a wet process includes oxalate precipitation, hydrothermal synthesis, and the like.
The solid phase method typically has disadvantages such as producing powder containing relatively large particles having a minimum particle size of about 1 micrometer, difficulties in controlling particle size, agglomeration of particles, contamination during the firing of particles, and the like, therefore, the solid phase method entails problems in the production of perovskite powder with regard to microparticles thereof.
In a variety of conventional processes, the tetragonality of dielectric particles generally deteriorates when the particle size thereof decreases. If the particle size is reduced to less than 100 nm, it is very difficult to secure a desired crystal axial ratio (c/a).
Further, with a decrease in the size of powder particles, dispersion of the powder becomes more difficult. Therefore, fine powder requires a high degree of dispersibility.
Existing solid phase methods or co-precipitation methods form a crystalline phase by high temperature calcination, therefore, requiring a high temperature calcining process and/or a grinding (or pulverization) process.
Due to the foregoing, synthesized perovskite powder entails problems such as poor morphology, broad particle size distribution, difficulties in dispersibility caused by the agglomeration of particles due to heat treatment, the generation of microfine particles after pulverization, and the like.
In the case in which the perovskite powder is synthesized by a hydrothermal process without heat treatment, the dispersion problem may be overcome. Moreover, hydrothermal synthesis may easily control the morphology of powder and enable the production of perovskite powder with a small particle size and a narrow distribution of particle sizes.
However, such a hydrothermal powder synthesis process has disadvantages in that a crystal structure has an oxygen site substituted by hydroxyl (—OH) group, causing defects such as the formation of pores. Therefore, it is difficult to improve the crystallinity of synthesized particles.